INTERNET DRAFT Pat R. Calhoun
Category: Standards Track Sun Microsystems, Inc.
Title: draft-calhoun-diameter-16.txt Allan C. Rubens
Date: July 2000 Tut Systems, Inc.
Haseeb Akhtar
Nortel Networks
Erik Guttman
Sun Microsystems, Inc.
DIAMETER Base Protocol
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at:
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at:
http://www.ietf.org/shadow.html.
This document is an individual contribution for consideration by the
AAA Working Group of the Internet Engineering Task Force. Comments
should be submitted to the diameter@diameter.org mailing list.
Distribution of this memo is unlimited.
Copyright (C) The Internet Society 1999. All Rights Reserved.
Calhoun et al. expires January 2001 [Page 1]
INTERNET DRAFT July 2000
Abstract
The DIAMETER base protocol is intended to provide a AAA framework for
Mobile-IP, NASREQ and ROAMOPS. This draft specifies the message
format, transport, error reporting and security services to be used
by all DIAMETER extensions and MUST be supported by all DIAMETER
implementations.
Table of Contents
1.0 Introduction
1.1 Requirements language
1.2 Terminology
2.0 Protocol Overview
2.1 Header Format
2.2 AVP Format
2.2.1 AVP Header
2.2.2 Optional Header Elements
2.2.3 AVP Value Formats
2.2.4 DIAMETER Base Protocol AVPs
2.3 Mandatory AVPs
2.3.1 Host-Name AVP
2.4 The art of AVP Tagging
2.5 State Machine
2.6 Device-Reboot-Ind (DRI) Command
2.6.1 Vendor-Name AVP
2.6.2 Firmware-Revision AVP
2.6.3 Extension-Id AVP
2.6.4 Host-IP-Address AVP
3.0 "User" Sessions
3.1 Session-Id AVP
3.2 Session-Timeout AVP
3.3 User-Name AVP
3.4 Session Termination
3.4.1 Session-Termination-Ind
3.4.2 Session-Termination-Request
3.4.3 Session-Termination-Answer
4.0 Reliable Transport
5.0 Error Reporting
5.1 Message-Reject-Ind (MRI) Command
5.1.1 Failed-AVP AVP
5.2 Result-Code AVP
6.0 DIAMETER Message Routing
6.1 NAI-Based Message Routing
6.2 Message Proxying
6.2.1 Proxy-State AVP
6.2.2 Destination-NAI AVP
Calhoun et al. expires January 2001 [Page 2]
INTERNET DRAFT July 2000
6.3 Message Redirection
6.3.1 Redirected-Host AVP
6.3.2 Redirect-Host-Port AVP
7.0 DIAMETER Message Security
7.1 Hop-by-Hop Security
7.1.1 Integrity-Check-Value AVP
7.1.2 Encrypted-Payload AVP
7.1.2.1 MD5 Payload Hiding
7.2 Nonce AVP
7.3 Timestamp AVP
8.0 IANA Considerations
8.1 AVP Attributes
8.2 Command Code AVP Values
8.3 Extension Identifier Values
8.4 Result-Code AVP Values
8.5 Integrity-Check-Value AVP Transform Values
8.6 AVP Header Bits
9.0 Open Issues
10.0 DIAMETER protocol related configurable parameters
11.0 Security Considerations
12.0 References
13.0 Acknowledgements
14.0 Authors' Addresses
15.0 Full Copyright Statement
Calhoun et al. expires January 2001 [Page 3]
INTERNET DRAFT July 2000
1.0 Introduction
The DIAMETER protocol allows peers to exchange a variety of messages.
The base protocol provides the following facilities:
- Delivery of AVPs (attribute value pairs)
- Capabilities negotiation, as required in [20]
- Error notification
- Extensibility, through addition of new commands and AVPs, as
required in [21]
All data delivered by the protocol is in the form of an AVP. Some of
these AVP values are used by the DIAMETER protocol itself, while
others deliver data associated with particular applications which
employ DIAMETER. AVPs may be added arbitrarily to DIAMETER messages,
so long as the required AVPs are included and AVPs which are
explicitly excluded are not included. AVPs are used by base DIAMETER
protocol to support the following required features:
- If application-level security is required, all messages MUST
include an Integrity Check Vector (ICV). If the ICV is present,
the message MUST also carry a timestamp and a nonce to aid in
providing replay protection.
- To carry user authentication information, for the purposes of
enabling the DIAMETER server to authenticate the user.
- To allow authorization information to be exchanged for a
particular user's session between a DIAMETER client and server.
- To exchange resource usage information, which MAY be used for
accounting purposes, capacity planning, etc.
The DIAMETER base protocol provides the minimum requirements needed
for an AAA transport protocol, as required by NASREQ [21], Mobile IP
[22, 23], and ROAMOPS [20]. The base protocol is not intended to be
used by itself, and must be used with an application-specific
extension, such as Mobile IP [10]. The DIAMETER protocol was heavily
inspired and builds upon the tradition of the RADIUS [1] protocol.
Any node can initiate a request. In that sense, DIAMETER is a peer to
peer protocol. In this document, a DIAMETER client is the device that
normally initiates a request for authentication and/or authorization
of a user. A DIAMETER server is the device that either forwards the
request to another DIAMETER server (known as a proxy), or one that
performs the actual authentication and/or authorization of the user
based on some profile. Given that the server MAY send unsocilited
messages to clients, it is possible for the server to also issue
authentication requests. However, these are typically in the form of
an indication that the user must be re-authenticated and/or re-
authorized. Another example of an unsolicited message would be for a
Calhoun et al. expires January 2001 [Page 4]
INTERNET DRAFT July 2000
request that the client issue an accounting update.
DIAMETER services require sequenced in-order reliable delivery of
data, with congestion control (receiver windowing). Timely detection
of failed or unresponsive peers is also required, allowing for robust
operation. TCP is insufficient for this second requirement.
DIAMETER SHOULD be transported over SCTP [26].
1.1 Requirements language
In this document, the key words "MAY", "MUST, "MUST NOT", "optional",
"recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as
described in [13].
1.2 Terminology
Refer to [9] for terminology used in this document.
2.0 Protocol Overview
The base DIAMETER protocol is never used on its own. It is always
extended for a particular application. Four extensions to DIAMETER
are defined by companion documents: NASREQ [7], Mobile IP [10],
Accounting Extension [15], Strong Security [11]. These options are
introduced in this document but specified elsewhere. Additional
extensions to DIAMETER may be defined in the future (see Section
8.3).
The base DIAMETER protocol concerns itself with capabilities
negotiation, and how messages are sent and how peers may eventually
be abandoned. The base protocol also defines certain rules which
apply to all exchanges of messages between DIAMETER peers. It is
important to note that the base protocol provides optional
application-level security AVPs (Integrity-Check-Value) which MAY be
used in absence of an underlying security protocol (e.g. IP
Security).
Communication between DIAMETER peers begins with one peer sending a
message to another DIAMETER peer. The set of AVPs included in the
message is determined by a particular application of or extension to
DIAMETER. We will refer to this as the DIAMETER extension. One AVP
that is included to reference a user's session is the Session-Id.
The initial request for authentication and/or authorization of a user
would include the Session-Id. The Session-Id is then used in all
Calhoun et al. expires January 2001 [Page 5]
INTERNET DRAFT July 2000
subsequent messages to identify the user's session (see section 3.0
for more information). The communicating party may accept the
request, or reject it by returning a response with Result-Code AVP
set to indicate an error occured. The specific behavior of the
diameter server or client receiving a request depends on the DIAMETER
extension employed.
Session state (associated with a Session-Id) MUST be freed upon
receipt of the Session-Termination-Request, Session-Termination-
Answer and according to rules established in a particular
extension/application of DIAMETER.
Exchanges of messages are either request/reply oriented, or in some
special cases, do not require replies. All such messages that do not
require replies have names ending with '-Ind' (short for Indication).
The DIAMETER base protocol provides the Session-Timeout AVP, which
MAY be used by extensions to specify the duration of a specific
authorized session.
2.1 Header Format
The base DIAMETER protocol is run over SCTP [26] port 1812.
Implementations MAY send packets from any source port, but MUST be
prepared to receive packets on port 1812. When a request is received,
in order to send a reply, the source and destination ports in the
reply are reversed. Note that the source and destination addresses
used in request and replies MAY be any of the peer's valid IP
addresses.
A given DIAMETER process SHOULD use the same port number to send all
messages to aid in identifying which process sent a given message.
More than one DIAMETER process MAY exist within a single host, so the
sender's port number is needed to discriminate them.
A summary of the DIAMETER data format is shown below. The fields are
transmitted in network byte order.
Calhoun et al. expires January 2001 [Page 6]
INTERNET DRAFT July 2000
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|RADIUS PCC=254 | Flags | Ver | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Command-Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVPs ...
+-+-+-+-+-+-+-+-+-+-+-+-+-
RADIUS PCC
The RADIUS Packet Compatibility Code (PCC) field is a one octet
field which is used for backward compatibility with RADIUS and
MUST be set to 254. In order to easily distinguish DIAMETER
messages from RADIUS, the value of 254 has been reserved and
allows implementations to support both protocols by using the
first octet in the header.
Flags
The Message Flags field is five bits, and is currently unused.
This field MUST be initialized to zero.
Version
This Version field MUST be set to 1 to indicate DIAMETER Version
1.
Message Length
The Message Length field is two octets and indicates the length of
the DIAMETER message including the header fields.
Identifier
The Identifier field is four octets, and aids in matching requests
and replies. The sender MUST ensure that the identifier in a
message is locally unique (to the sender) at any given time, and
MAY attempt to ensure that the number is unique across reboots.
The identifier is normally a monotonically increasing number,
whose start value was randomly generated. DIAMETER servers should
consider a message to be unique by examining the source address,
source port and Identifier field of the message.
Command-Code
The Command-Code field is four octets, and is used in order to
communicate the command associated with the message. The 32-bit
address space is managed by IANA (see section 8.2). The following
Calhoun et al. expires January 2001 [Page 7]
INTERNET DRAFT July 2000
Command Codes are currently defined in the DIAMETER base protocol
and extensions:
Command-Name Abbrev. Code Reference
--------------------------------------------------------
Device-Reboot-Ind DRI 257 2.6
Message-Reject-Ind MRI 259 5.1
Session-Termination-Ind STI 274 3.4.1
Session-Termination- STR 275 3.4.2
Request
Session-Termination- STA 276 3.4.3
Answer
AA-Mobile-Node-Request AMR 260 [10]
AA-Mobile-Node-Answer AMA 261 [10]
Home-Agent-MIP-Request HAR 262 [10]
Home-Agent-MIP-Answer HAA 263 [10]
AA-Request AAR 265 [7]
AA-Answer AAA 266 [7]
AA-Challenge-Ind ACI 267 [7]
DIAMETER-EAP-Request DER 268 [7]
DIAMETER-EAP-Answer DEA 269 [7]
DIAMETER-EAP-Ind DEI 270 [7]
Accounting-Request ACR 271 [15]
Accounting-Answer ACA 272 [15]
Accounting-Poll-Ind ACP 273 [15]
Accounting-Status-Ind ASI 279 [15]
Session-Resource-Query SRQ 277 [29]
Session-Resource-Reply SRR 278 [29]
Vendor-ID
In the event that the Command-Code field contains a vendor
specific command, the four octet Vendor-ID field contains the IANA
assigned "SMI Network Management Private Enterprise Codes" [2]
value. If the Command-Code field contains an IETF standard
Command, the Vendor-ID field MUST be set to zero (0).
AVPs
AVPs is a method of encapsulating information relevant to the
DIAMETER message. See section 2.2 for more information on AVPs.
2.2 AVP Format
DIAMETER AVPs carry specific authentication, accounting and
authorization information, security information as well as
configuration details for the request and reply.
Some AVPs MAY be listed more than once. The effect of this AVP is
Calhoun et al. expires January 2001 [Page 8]
INTERNET DRAFT July 2000
specific, and is specified in each case by the AVP description.
Each AVP of type 'string' and 'data' MUST be padded to align on a 32
bit boundary, while other AVP types align naturally. NULL bytes are
added to the end of the AVP value till a word boundary is reached.
The length of the padding is not reflected in the AVP Length field.
2.2.1 AVP Header
The AVP format is shown below and MUST be sent in network byte order.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AVP Length | Reserved |P|T|V|R|M|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vendor-ID (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tag (opt) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-+-+-+-+
AVP Code
The AVP Code identifies the attribute uniquely. The first 256 AVP
numbers are reserved for backward compatibility with RADIUS and
are to be interpreted as per NASREQ [7]. AVP numbers 256 and above
are used for DIAMETER, which are allocated by IANA (see section
8.1).
AVP Length
The AVP Length field is two octets, and indicates the length of
this Attribute including the AVP Code, AVP Length, AVP Flags,
Reserved, the Tag and Vendor-ID fields if present and the AVP
data. If a message is received with an Invalid attribute length,
the message SHOULD be rejected.
AVP Flags
The AVP Flags field informs the DIAMETER host how each attribute
must be handled. Note that subsequent DIAMETER extensions MAY
define bits to be used within the AVP Header, and an unrecognized
bit should be considered an error. The 'R' and the reserved bits
are unused and should be set to 0 and ignored on receipt, while
the 'P' bit is defined in [11].
Calhoun et al. expires January 2001 [Page 9]
INTERNET DRAFT July 2000
The 'M' Bit, known as the Mandatory bit, indicates whether support
of the AVP is required. If an AVP is received with the 'M' bit
enabled and the receiver does not support the AVP, the message
MUST be rejected. AVPs without the 'M' bit enabled are
informational only and a receiver that receives a message with
such an AVP that is not supported MAY simply ignore the AVP.
The 'V' bit, known as the Vendor-Specific bit, indicates whether
the optional Vendor-ID field is present in the AVP header. When
set the AVP Code belongs to the specific vendor code address
space.
The 'T' bit, known as the Tag bit, is used to group sets of AVPs
together. Grouping of AVPs is necessary when more than one AVP is
needed to express a condition. If this bit is set, the optional
Tag field will be present.
Unless otherwise noted, AVPs will have the following default AVP
Flags field settings:
The 'M' bit MUST be set. The 'V' bit MUST NOT be set. The 'T'
bit MAY be set.
2.2.2 Optional Header Elements
The AVP Header consists of several optional fields. These fields are
only present if their respective bit-flags are enabled.
Vendor-ID
The Vendor-ID field is present in the 'V' bit is set in the AVP
Flags field. The optional four octet Vendor-ID field contains the
IANA assigned "SMI Network Management Private Enterprise Codes"
[2] value, encoded in network byte order. Any vendor wishing to
implement a DIAMETER extensions MUST use their own Vendor-ID along
with their privately managed AVP address space, guaranteeing that
they will not collide with any other vendor's extensions, nor with
future IETF extensions.
A vendor ID value of zero (0) corresponds to the IETF adopted AVP
values, as managed by the IANA. Since the absence of the vendor ID
field implies that the AVP in question is not vendor specific,
implementations SHOULD not use the zero (0) vendor ID.
Tag
The Tag field is four octet in length and is intended to provide a
means of grouping attributes in the same message which refer to
the same set. If the Tag field is unused, the 'T' bit MUST NOT be
set (see section 2.4 for more information).
Calhoun et al. expires January 2001 [Page 10]
INTERNET DRAFT July 2000
2.2.3 AVP Value Formats
The Data field is zero or more octets and contains information
specific to the Attribute. The format and length of the Data field is
determined by the AVP Code and AVP Length fields. The format of the
value field MAY be one of seven data types.
Data
The data contains a variable length of arbitrary data. Unless
otherwise noted, the AVP Length field MUST be set to at least
9.
String
The data contains a non-NULL terminated variable length string
using the UTF-8 [24] character set. Unless otherwise noted,
the AVP Length field MUST be set to at least 9.
Address
32 bit (IPv4) [17] or 128 bit (IPv6) [16] address, most
significant octet first. The format of the address (IPv4 or
IPv6) is determined by the length. If the attribute value is an
IPv4 address, the AVP Length field MUST be 12, otherwise the
AVP Length field MUST be set to 24 for IPv6 addresses.
Integer32
32 bit value, in network byte order. The AVP Length field MUST
be set to 12.
Integer64
64 bit value, in network byte order. The AVP Length field MUST
be set to 16.
Time
32 bit unsigned value contains the four most significant octets
returned from NTP [18], in network byte order. The AVP Length
field MUST be set to 12.
Complex
The complex data type is reserved for AVPs that includes
multiple information fields, and therefore do not fit within
any of the AVP types defined above. Complex AVPs MUST provide
the data format, and the expected length of the AVP.
2.2.4 DIAMETER Base Protocol AVPs
The following table describes the DIAMETER AVPs defined in the base
protocol, their AVP Code values, types, possible flag values and
Calhoun et al. expires January 2001 [Page 11]
INTERNET DRAFT July 2000
whether the AVP MAY be encrypted.
+---------------------+
| AVP Flag rules |
|----+-----+----+-----|----+
AVP Section Value | | |SHLD| MUST|MAY |
Attribute Name Code Defined Type |MUST| MAY | NOT| NOT|Encr|
-----------------------------------------|----+-----+----+-----|----|
User-Name 1 3.3 String | | | | | Y |
Session-Timeout 27 3.2 Integer32| | | | | Y |
Proxy-State 33 6.2.1 Complex | M | | | T,V | N |
Host-IP-Address 257 2.6.4 Address | M | | | T,V | N |
Extension-Id 258 2.6.3 Integer32| | | | | Y |
Integrity-Check 259 7.1.1 Complex | | | | | N |
-Value | | | | | |
Encrypted- 260 7.1.2 Complex | | | | | N |
Payload | | | | | |
Nonce 261 7.2 Data | | | | | N |
Timestamp 262 7.3 Time | | | | | N |
Session-Id 263 3.3 Data | | | | | Y |
Host-Name 264 2.3.2 String | M | | | T,V | N |
Vendor-Name 266 2.6.1 String | | | |T,V,M| Y |
Firmware 267 2.6.2 Integer32| | | |T,V,M| Y |
-Revision | | | | | |
Result-Code 268 5.2 Complex | | | | | N |
Destination-NAI 269 6.2.2 String | | | | | Y |
Failed-AVP 279 5.1.1 Data | | | | | Y |
Redirect-Host 278 6.3.1 Address | | | | | Y |
Redirect-Host- 277 6.3.2 Integer32| | | | | Y |
Port | | | | | |
2.2.5 Standard DIAMETER Extension AVPs
The following AVPs are defined in standard DIAMETER extensions.
Calhoun et al. expires January 2001 [Page 12]
INTERNET DRAFT July 2000
AVP Name Code Ref AVP Name Code Ref AVP Name Code Ref
------------- ---- --- ------------ ---- --- ------------ ---- ----
User-Password 2 [7] Framed- 38 [7] MN-FA- 322 [10]
CHAP-Password 3 [7] Appletalk- Challenge-
NAS-IP-Address 4 [7] Network Length
NAS-Port 5 [7] Framed- 39 [7] MN-FA-Response 323 [10]
Service-Type 6 [7] Appletalk- Mobile-Node- 333 [10]
Framed-Protocol 7 [7] Zone Address
Framed-IP- 8 [7] CHAP-Challenge 60 [7] Home-Agent- 334 [10]
Address NAS-Port-Type 61 [7] Address
Framed-IP- 9 [7] Port-Limit 62 [7] Previous-FA- 335 [10]
Netmask Login-LAT-Port 63 [7] NAI
Framed-Routing 10 [7] Tunnel-Type 64 [7] MN-AAA-SPI 336 [10]
Filter-Id 11 [7] Tunnel-Medium- 65 [7] Foreign-Home- 337 [10]
Framed-MTU 12 [7] Type Agent-
Framed- 13 [7] Tunnel-Client- 66 [7] Available
Compression Endpoint Filter-Rule 400 [7]
Login-IP-Host 14 [7] Tunnel-Server- 67 [7] Request-Type 401 [7]
Login-Service 15 [7] Endpoint EAP-Payload 402 [7]
Login-TCP-Port 16 [7] Tunnel-Password 69 [7] Accounting- 480 [15]
Reply-Message 18 [7] Tunnel-Private- 81 [7] Record-Type
Callback-Number 19 [7] Group-ID ADIF-Record 481 [15]
Callback-Id 20 [7] Tunnel- 82 [7] Accounting- 482 [15]
Framed-IP-Route 22 [7] Assignment-ID Interim-
Framed-IPX- 23 [7] Tunnel- 83 [7] Interval
Route Preference Accounting- 483 [15]
Idle-Timeout 28 [7] Tunnel-Client- 90 [7] Delivery-
Called-Station- 30 [7] Auth-ID Interval
Id Tunnel-Server- 91 [7] Accounting- 484 [15]
Calling- 31 [7] Auth-ID Delivery-
Station-Id CMS-Data 310 [11] Max-Delay
NAS-Identifier 32 [7] MIP- 320 [10] Accounting- 485 [15]
Login-LAT- 34 [7] Registration- Record-
Service Request Number
Login-LAT-Node 35 [7] MIP- 321 [10] Accounting-
Login-LAT-Group 36 [7] Registration- State 486 [15]
Framed- 37 [7] Reply Query-Index 500 [29]
Appletalk- Resource-Token 501 [29]
Link
2.3 Mandatory AVPs
This section defines the DIAMETER AVPs that MUST be present in all
DIAMETER messages.
2.3.1 Host-Name AVP
Calhoun et al. expires January 2001 [Page 13]
INTERNET DRAFT July 2000
The Host-Name AVP (AVP Code 264) [1] is of type String, and is used
to inform a DIAMETER peer of the sender's identity. All DIAMETER
messages MUST include the Host-Name AVP, which contains the host name
of the originator of the DIAMETER message that MUST follow the NAI
[8] naming conventions.
Note that the Host-Name AVP may resolve to more than one address as
the DIAMETER peer may support more than one address.
2.4 The art of AVP Tagging
The AVP Header provides the 'T' bit, which is used to group AVPs
together. All AVPs with the same tag value are part of the same
"group", known as a "tagged AVP set", and there are no guidelines or
rules on which tag values are used. The base protocol defines the
Redirect-Host AVP (see section 6.3.1), and [11] defines how the
associated certificate MAY be carried within the DIAMETER protocol.
This allows a single request to include information about more than
one host. In the case where multiple AVPs are needed to indicate a
specific authorization "rule" tagging is appropriate. In some cases,
more than one such rule MAY be present, and the tagging mechanism
allows the sets of AVPs to be easily grouped.
Some Command Codes require certain AVPs to be tagged. Tagged AVPs are
represented in the BNF command definition through the use of the '('
and ')' characters. All AVPs within a single tagged AVP set MUST all
contain the same tag value, but no two sets MAY use the same tag
value.
<Device-Reboot-Ind> ::= <DIAMETER Header, Command-Code = foobar>
(<Tagged AVP #1>
<Tagged AVP #2>
<Tagged AVP n>)
2.5 State Machine
This section contains a finite state machine, that MUST be observed
by all DIAMETER implementations. Each DIAMETER node MUST follow the
state machine described below when communicating with each peer.
State Event Action New State
----- ----- ------ ---------
Initial Local request to establish SCTP Idle
communication with a DIAMETER Connect
peer with which there is no
existing transport level
Calhoun et al. expires January 2001 [Page 14]
INTERNET DRAFT July 2000
connection established.
Initial Receive transport level Send DRI Open
connection request from a
DIAMETER peer.
Idle Connection Established Send DRI Wait-DRI
Idle Receive DRI Send DRI Open
Wait-DRI Receive DRI None Open
Open Receive other messages Process Open
Message
Open Receive DRI Cleanup Closed
Open Transport level failure Cleanup Closed
Closed DIAMETER Entity shutdown Close Initial
or close connection with peer connection
The Initial and Idle states MAY be merged if the local SCTP
implementation is able to implement the piggyback of data during the
connection phase.
When the Cleanup action is invoked, the DIAMETER node SHOULD attempt
to forward all pending requests and replies, which haven't been
acknowledged, to an alternate server (when possible). If the final
destination for a specific message is the host that is no longer
accessible, the message in question SHOULD be responded with the
Result-Code AVP set to DIAMETER_UNABLE_TO_DELIVER.
2.6 Device-Reboot-Ind (DRI) Command
A DIAMETER device sends the Device-Reboot-Ind message, by setting the
Command-Code field with a value of 257, to inform a peer that a
reboot has just occured. Since SCTP [26] allows for connections to
span multiple interfaces, hence multiple IP addresses, the Device-
Reboot-Ind message MUST contain one Host-IP-Address AVP for each
potential IP address that MAY be locally used when transmitting
DIAMETER messages.
The DRI message is also used for capabilities negotiation, such as
the supported protocol version number, and the locally supported
extensions. The receiver uses the extensions advertised in order to
determine whether it SHOULD send certain application-specific
Calhoun et al. expires January 2001 [Page 15]
INTERNET DRAFT July 2000
DIAMETER commands. A DIAMETER node MUST retain the supported
extensions in order to ensure that unrecognized commands and/or AVPs
are not sent to a peer. Note that in a proxy environment, it is still
possible that a downstream proxy has no available peer that have
advertised the extension that corresponds to the Command-Code, and
therefore the request cannot be forwarded any further. The DIAMETER
base protocol provides this error reporting, via the Result-Code AVP.
Once the transport layer connection has been established, a DIAMETER
entity MUST issue a DRI message, regardless of whether the peer was
statically configured, or dynamically discovered. Dynamic discovery
of DIAMETER peers MAY be done by using Service Location Protocol
(SLP) [28], or through some other discovery mechanism.
If a peer is no longer reachable, a DIAMETER device SHOULD
periodically attempt to establish a transport level connection with
the peer and send a DRI message. This message does not require a
reply. If a DIAMETER node receives a DRI message that results in an
error, a Message-Reject-Ind message MUST be returned.
Message Format
<Device-Reboot-Ind> ::= <DIAMETER Header, Command-Code = 257>
<Host-Name AVP>
<Host-IP-Address AVP>
<Vendor-Name AVP>
<Extension-Id AVPs>
[<Firmware-Revision AVP>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Value AVP>]
2.6.1 Vendor-Name AVP
The Vendor-Name AVP (AVP Code 266) is of type String and is used to
inform a DIAMETER peer of the Vendor Name of the DIAMETER device.
This MAY be used in order to know which vendor specific attributes
may be sent to the peer. It is also envisioned that the combination
of the Vendor-Name and the Firmware-Revision (section 2.6.2) AVPs MAY
provide very useful debugging information.
2.6.2 Firmware-Revision AVP
The Firmware-Revision AVP (AVP Code 267) is of type Integer32 and is
used to inform a DIAMETER peer of the firmware revision of the
issuing device.
Calhoun et al. expires January 2001 [Page 16]
INTERNET DRAFT July 2000
For devices that do not have a firmware revision (general purpose
computers running DIAMETER software modules, for instance), the
revision of the DIAMETER software module may be reported instead.
2.6.3 Extension-Id AVP
The Extension-Id AVP (AVP Code 258) is of type Integer32 and is used
in order to identify a specific DIAMETER extension. This AVP is used
in the Device-Reboot-Ind message in order to inform the peer what
extensions are locally supported.
Each DIAMETER extension draft MUST have an IANA assigned extension
Idenfier (see section 8.3). The base protocol does not require an
Extension-Id since its support is mandatory.
There MAY be more than one Extension-Id AVP within a DIAMETER
Device-Reboot-Ind message. The following values are recognized:
NASREQ 1 [7]
Strong Security 2 [11]
Resource Management 3 [29]
Mobile-IP 4 [10]
Accounting 5 [15]
2.6.4 Host-IP-Address AVP
The Host-IP-Address AVP (AVP Code 4) [1] is of type Address and is
used to inform a DIAMETER peer of the sender's IP addresses. All
source addresses that a DIAMETER node expects to use with SCTP [26]
MUST be advertised in the Device-Reboot-Ind message by including a
Host-IP-Address AVP for each address. This AVP MUST ONLY be used in
the Device-Reboot-Ind message.
3.0 "User" Sessions
When a user requests access to the network, a DIAMETER client issues
an authentication and authorization request to its local server. The
request contains a Session-Id AVP, which is used in subsequent
messages (e.g. subsequent authorization, accounting, etc) relating to
the user's session. The Session-Id AVP is a means for the client and
servers to correlate a DIAMETER message with a user session.
When a DIAMETER server authorizes a user to use network resources, it
SHOULD add the Session-Timeout AVP to the response. The Session-
Timeout AVP defines the maximum amount of time a user MAY make use of
Calhoun et al. expires January 2001 [Page 17]
INTERNET DRAFT July 2000
the resources before another authorization request is to be
transmitted to the server. If the server does not receive another
authorization request before the timeout occurs, it SHOULD release
any state information related to the user's session. Note that the
Session-Timeout AVP implies how long the DIAMETER server is willing
to pay for the services rendered, therefore a DIAMETER client SHOULD
NOT expect payment for services rendered past the session expiration
time.
The base protocol does not include any authorization request
messages, since these are largely application-specific and are
defined in a DIAMETER protocol extension document. However, the base
protocol does define a set of messages that are used to terminate
user sessions. These are used to allow servers that maintain state
information to free resources.
3.1 Session-Id AVP
The Session-Id AVP (AVP Code 263) is of type Data and is used to
identify a specific session (see section 3.0). All messages
pertaining to a specific session MUST include only one Session-Id AVP
and the same value MUST be used throughout the life of a session.
When present, the Session-Id SHOULD appear immediately following the
DIAMETER Header (see section 2.1).
For messages that do not pertain to a specific session, multiple
Session-Id AVPs MAY be present as long as the 'T' bit is set.
The Session-Id MUST be globally unique at any given time since it is
used by the server to identify the session (or flow). The format of
the session identifier SHOULD be as follows:
<Sender's Host-Name><sender's port number> <monotonically increasing
32 bit value><optional value>
The monotonically increasing 32 bit value SHOULD NOT start at zero
upon reboot, but rather start at a random value. This will minimize
the possibility of overlapping Session-Ids after a reboot.
Alternatively, an implementation MAY keep track of the increasing
value in non-volatile memory. The optional value is implementation
specific but may include a modem's device Id, a layer 2 address,
timestamp, etc.
The session Id is created by the DIAMETER device initiating the
session, which in most cases is done by the client. Note that a
Session-Id MAY be used by more than one extension (e.g.
authentication for a specific service and accounting, both of which
Calhoun et al. expires January 2001 [Page 18]
INTERNET DRAFT July 2000
have separate extensions).
3.2 Session-Timeout AVP
The Session-Timeout AVP (AVP Code 27) [1] is of type Integer32 and
contains the maximum number of seconds of service to be provided to
the user before termination of the session. A value of zero means
that this session has an unlimited number of seconds before
termination.
This AVP MAY be provided by the client as a hint of the maximum
duration that it is willing to accept. However, the server DOES NOT
have to observe the hint, and MAY return a value that is smaller than
the hint. A value of zero provided by a client DOES NOT imply that
service is being terminated.
3.3 User-Name AVP
The User-Name AVP (AVP Code 1) [1] is of type String and contains the
User-Name in a format consistent with the NAI specification [8]. All
DIAMETER systems SHOULD support usernames of at least 72 octets in
length.
3.4 Session Termination
The DIAMETER Base Protocol provides a set of messages that MAY be
used by any peer to explicitely request that a previously
authenticated and/or authorized session be terminated. Since the
Session-Id is typically tied to a particular service (i.e. Mobile IP,
NASREQ, etc), the session termination messages are used to request
that the service tied to the Session Id be terminated.
3.4.1 Session-Termination-Ind
The Session-Termination-Ind (STI), indicated by the Command-Code set
to 274, MAY be sent by any DIAMETER entity to the access device to
request that a particular session be terminated. This message MAY be
used when a server detects that a session MUST be terminated, which
is typically done as a policy decision (e.g. local resources have
been expended, etc). The Destination-NAI AVP MUST be present, and
contain the NAI of the access device that initiated the session (see
section 3.0).
Upon receipt of the STI message, the access device SHOULD issue a
Calhoun et al. expires January 2001 [Page 19]
INTERNET DRAFT July 2000
Session-Terminate-Request message.
Message Format
<Session-Termination-Ind> ::= <DIAMETER Header, Command-Code =
274>
<Session-Id AVP>
<Host-Name AVP>
<User-Name AVP>
<Destination-NAI AVP>
[<Proxy-State AVP>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Value AVP>]
3.4.2 Session-Termination-Request
The Session-Termination-Request (STR), indicated by the Command-Code
set to 275, is sent by the access device to inform the Home AAA that
an authenticated and/or authorized session is being terminated. The
Destination-NAI AVP MUST be present, and set to the value that was
found in the Host-Name AVP of the authentication and/or authorization
response that corresponds with the session in question (e.g. AAA,
HAR, AMA in section 2.1).
Upon receipt of the STR, the Home DIAMETER Server SHOULD release all
resources for the session indicated by the Session-Id AVP. Any
intermediate server in the Proxy-Chain MAY also release any
resources, if necessary.
Message Format
<Session-Termination-Request> ::= <DIAMETER Header, Command-Code
= 275>
<Session-Id AVP>
<Host-Name AVP>
<User-Name AVP>
<Destination-NAI AVP>
[<Proxy-State AVP>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Value AVP>]
3.4.3 Session-Termination-Answer
The Session-Termination-Answer (STA), indicated by the Command-Code
set to 276, is sent by the Home DIAMETER Server to acknowledge that
Calhoun et al. expires January 2001 [Page 20]
INTERNET DRAFT July 2000
the session has been terminated. The Result-Code AVP MUST be present,
and MAY contain an indication that an error occured while servicing
the STR.
Message Format
<Session-Termination-Answer> ::= <DIAMETER Header, Command-Code =
276>
<Result-Code AVP>
<Session-Id AVP>
<Host-Name AVP>
<User-Name AVP>
<Destination-NAI AVP>
[<Proxy-State AVP>]
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Value AVP>]
4.0 Reliable Transport
In order to provide rapid discovery of the failure of a communicating
peer, aggressive retransmission and rapid transactions, DIAMETER
peers MUST be able to send and receive messages over SCTP [26]. A
DIAMETER peer MAY use TCP [27], as TCP does provide reliable
transport, though it does not have the properties listed above.
5.0 Error Reporting
There are five different types of errors within DIAMETER. The first
being where a DIAMETER message is poorly formatted and
unrecognizable, indicated below by "Bad Message". This error
condition applies if a received message creates a fatal error (e.g.
fails transport level authentication, cannot be parsed, etc).
The second case involves receiving a Command-Code that is not
supported, which is shown below by "Unknown Command". The third case
is where an AVP is received, marked mandatory and is unknown by the
receiver, which is labeled below as "Unknown AVP".
This fourth case involves receiving a message with a known AVP, yet
the value is either unknown or illegal, which is shown below as "Bad
Value". The last case occurs when an error occurs while processing a
specific extension command, which is not related to the message
format and is labeled "Extension Error" below.
Calhoun et al. expires January 2001 [Page 21]
INTERNET DRAFT July 2000
Error Type Ignore Message Send Extension
Message-Reject-Ind Response +
Result-Code
Bad Message X
Unknown Command X
Unknown AVP X
Bad Value X
Extension Error X
"Ignore Message" indicates that the message is simply dropped. The
"Message-Reject-Ind" indicates that a Message-Reject-Ind message MUST
be sent to the peer as described in the appropriate section. The
"Extension Response + Result-Code" indicates that the appropriate
Response to the message MUST be sent with the Result-Code AVP set to
a value that enables the peer to understand the nature of the
problem.
5.1 Message-Reject-Ind (MRI) Command
The Message-Reject-Ind (MRI), indicated by the Command-Code set to
259, provides a generic means of completing transactions by
indicating errors in the messages that initiated them. The Message-
Reject-Ind command is sent in response:
1. An error is found in a Device-Reboot-Ind message.
2. An error is found in a message for which there is no
appropriate response.
3. A message was received that cannot pass the base protocol error
checking.
4. A message was received whose extension is not locally
supported.
In the event that a request is received that causes an error defined
in a DIAMETER extension, the appropriate response with the Result-
Code AVP SHOULD be sent.
The Message-Reject-Ind message MUST contain the same identification
in the header and include the Session-Id if it was present in the
original message that it is responding to, even if the identification
is erroneous.
Message Format
The structure of the Message-Reject-Ind message is defined as
follows:
Calhoun et al. expires January 2001 [Page 22]
INTERNET DRAFT July 2000
<Message-Reject-Ind message> ::= <DIAMETER Header, Command-Code =
259>
<Host-Name AVP>
[<Session-Id AVP>]
<Result-Code AVP>
<Failed-AVP AVP>
[<Timestamp AVP>
<Nonce AVP>
<Integrity-Check-Value AVP>]
where the Identifier value in the message header and optionally
the Session-Id AVP are copied from the message being rejected. The
Result-Code AVP indicate the nature of the error causing
rejection, and the Failed-AVP AVP provides some minimal debugging
data by indicating a specific AVP type which caused the problem.
See the description of the Result-Code AVP for indication of when
the Failed-AVP AVP MUST be present in the message. See [25] for
more information.
5.1.1 Failed-AVP AVP
The Failed-AVP AVP (AVP Code 279) is of type Data and provides
debugging information in cases where a request is rejected or not
fully processed due to erroneous information in a specific AVP. The
value of the Result-Code AVP will provide information on the reason
for the Failed-AVP AVP.
A DIAMETER message MAY contain one or more Failed-AVP, each
containing a complete AVP that could not be processed successfully.
The possible reasons for this AVP are the presence of an improperly
constructed AVP, an unsupported or unrecognized AVP or an invalid AVP
value (e.g. unknown Command-Code).
5.2 Result-Code AVP
The Result-Code AVP (AVP Code 268) is of type Complex and indicates
whether a particular request was completed successfully or whether an
error occurred. All DIAMETER messages of type *-Response or *-Answer
MUST include one Result-Code AVP.
Calhoun et al. expires January 2001 [Page 23]
INTERNET DRAFT July 2000
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
AVP Header (AVP Code = 268)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Result Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| String ...
+-+-+-+-+-+-+-+-+
The Result Code field contains an IANA-managed 32-bit address space
representing errors (see section 8.4). The String field contains an
OPTIONAL string field containing a human readable error message. The
base protocol defines the following error codes, and others MAY be
defined in separate DIAMETER extensions:
DIAMETER_SUCCESS 0
The Request was successfully completed.
DIAMETER_FAILURE 1
The Request was not successfully completed for an unspecified
reason. A DIAMETER Message-Reject-Ind message returning this
result SHOULD whenever possible also contain one or more
Failed-AVP AVPs indicating the AVPs that caused the failure.
DIAMETER_POOR_REQUEST 2
The Request was poorly constructed.
DIAMETER_INVALID_AUTH 3
The Request did not contain a valid Integrity-Check-Value or
CMS-Data [11] AVP.
DIAMETER_UNKNOWN_SESSION_ID 4
The request or response contained an unknown Session-Id.
DIAMETER_USER_UNKNOWN 5
A request was received for a user that is unknown, therefore
authentication failed. This error is sent only due to
conditions that arise due to command messages in DIAMETER
extensions, the base protocol does not include command codes
that require the User-Name AVP.
DIAMETER_COMMAND_UNSUPPORTED 6
The Request contained a Command-Code that the receiver did not
recognize or support. The Message-Reject-Ind message MUST also
contain a Failed-AVP AVP containing the unrecognized Command-
Code.
Calhoun et al. expires January 2001 [Page 24]
INTERNET DRAFT July 2000
DIAMETER_TIMEOUT 7
This error MAY be returned if a request has been received that
has a Timestamp AVP that is older than the maximum age that the
communicating peer is willing to accept.
DIAMETER_AVP_UNSUPPORTED 8
The peer received a message that contained an AVP that is not
recognized or supported and was marked with the Mandatory bit.
A DIAMETER message with this error MUST contain one or more
Failed-AVP AVP containing the AVPs that caused the failure.
DIAMETER_REDIRECT_INDICATION 9
A proxy or broker has determined that the request could not be
satisfied locally and the initiator of the request should
direct the request directly to the server, whose contact
information has been added to the response. This error code
MUST NOT be sent in a Message-Reject-Ind message.
DIAMETER_REALM_NOT_SERVED 10
A proxy or broker has determined that it is unable to forward
the request or provide redirect information since the realm
portion of the NAI requested is unknown.
DIAMETER_UNSUPPORTED_TRANSFORM 11
A message was received that included an Integrity-Check-Value
or CMS-Data AVP [11] that made use of an unsupported transform.
DIAMETER_AUTHENTICATION_REJECTED 12
The authentication process for the user failed, most likely due
to an invalid password used by the user.
DIAMETER_AUTHORIZATION_REJECTED 13
A request was received for which the user could not be
authorized. This error could occur when the user has already
expended allowed resources, or if the service requested is not
permitted to the user.
DIAMETER_INVALID_AVP_VALUE 14
The request contained an AVP with an invalid value in its data
portion. A DIAMETER message with this result code MUST include
the offending AVPs within a Failed-AVP AVP.
DIAMETER_MISSING_AVP 15
The request did not contain an AVP that is considered mandatory
by the Command Code definition. If this value is sent in the
Result-Code AVP, a Failed-AVP AVP SHOULD be included in the
message. The data portion of the Failed-AVP MUST have its AVP
Code set to the value of the missing AVP.
Calhoun et al. expires January 2001 [Page 25]
INTERNET DRAFT July 2000
DIAMETER_UNABLE_TO_DELIVER 16
The request could not be delivered to the host specified in the
Destination-NAI AVP, or no host is available for that
particular realm to handle the request.
5.2.1 Additional Error Codes
The following additional result codes are defined by standard
extensions to the DIAMETER protocol.
DIAMETER_ERROR_BAD_KEY 16 [10]
DIAMETER_ERROR_BAD_HOME_ADDRESS 17 [10]
DIAMETER_ERROR_TOO_BUSY 18 [10]
DIAMETER_ERROR_MIP_REPLY_FAILURE 19 [10]
DIAMETER_INVALID_CMS_DATA 20 [11]
6.0 DIAMETER Message Routing
The DIAMETER base protocol supports two basic message routing
methods; proxying and brokering. A DIAMETER proxy is a server that
simply forwards the request based on the user's identity, or through
some other means. A DIAMETER broker is a server that provides
redirect services, allowing all servers in a roaming consortium to
interact directly. This section describes how DIAMETER message
routing is performed.
6.1 NAI-Based Message Routing
DIAMETER Message routing is done through the use of the Network
Access Identifier (NAI), and an associated realm routing table (see
section 10.0). The NAI has a format of user@realm, and DIAMETER
servers have a list of locally supported realms, and MAY have a list
of externally supported realms. When a message is received that
includes a realm that is not locally supported, the message is
proxied to the DIAMETER entity configured in the "route" table.
Figure 1 depicts an example where DIA1 receives a request to
authenticate user "joe@abc.com". DIA1 looks up "abc.com" in its local
realm route table and determines that the message must be proxied to
DIA2. DIA2 does the same check, and proxies the message to DIA3. DIA3
checks its realm route table, and determines that the realm is
locally supported, and processes the authentication request, and
returns the response. How the response actually makes it back to the
sender of the original request is described in the next section.
Calhoun et al. expires January 2001 [Page 26]
INTERNET DRAFT July 2000
(Request) (Request)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
+------+ ------> +------+ ------> +------+
| | | | | |
| DIA1 +-------------------+ DIA2 +-------------------+ DIA3 |
| | | | | |
+------+ <------ +------+ <------ +------+
(Response) (Response)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
mno.net xyz.com abc.com
Figure 1: NAI Based Routing
6.2 Message Proxying
A DIAMETER proxy is a server that provides message forwarding
functions to other DIAMETER Servers. Proxies are typically used when
a hierarchical DIAMETER network is deployed, where some DIAMETER
servers can authenticate and authorize a set of users. Such an
example is a roaming consortium, where each ISP has a user base,
which they can authenticate and authorize. It is important to note
that proxy servers MUST NOT attempt to re-order AVPs in a DIAMETER
message.
There are two different methods of routing DIAMETER messages through
proxies; Proxy-State and Destination-NAI. The Proxy-State AVP is used
to encode local state information in a request. The corresponding
response is guaranteed to include the same Proxy-State AVP, allowing
the node to recover the state information. The use of the Proxy-State
AVP requires that the corresponding response traverse through the
same set of proxies (in reverse order), which introduces some
reliability problems. If a single DIAMETER node in the proxy chain
fails, all responses that must traverse through it would be lost. The
Proxy-State AVP is used by proxy servers that MUST maintain state
information, such as protocol translation gateways [25].
The Destination-NAI is a more flexible scheme, and is used by
DIAMETER proxies that do not need to maintain any state information
when acting as a simple message routing agent. This allows the
DIAMETER network to be much more reliable, since responses can be
sent through an alternate path should a proxy server fail.
6.2.1 Proxy-State AVP
The Proxy-State AVP (AVP Code 33) [1] is used by proxy servers when
forwarding requests and contains opaque data that is used by the
Calhoun et al. expires January 2001 [Page 27]
INTERNET DRAFT July 2000
proxy to further process the response. Such data may include AVPs
that are to be added to the response, information about the
downstream peer, etc.
It is important to note that the use of the Proxy-State AVP requires
that the corresponding response traverse through the DIAMETER node
that added the AVP. The requirement that responses return on the
reverse path of a request is only adequate in certain networks. It
does not allow for resilient operation, since alternative servers
MUST NOT be used. Therefore a DIAMETER node SHOULD only use the
Proxy-State AVP when performing protocol bridging [25].
A DIAMETER node that adds a Proxy-State AVP to a request expects the
SAME AVP to be present in the corresponding response. Furthermore,
more than one Proxy-State AVP MUST NOT be present in a single
DIAMETER message. See [25] for more information on AVP handling.
(Request) (Request)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
(Proxy-State=DIA1,x) (Proxy-State=DIA2,y)
+------+ ------> +------+ ------> +------+
| | | | | |
| DIA1 +-------------------+ DIA2 +-------------------+ DIA3 |
| | | | | |
+------+ <------ +------+ <------ +------+
(Response) (Response)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
(Proxy-State=DIA1,x) (Proxy-State=DIA2,y)
mno.net xyz.com abc.com
Figure 2: Use of the Proxy-State AVP
When a DIAMETER node receives a message that includes the Proxy-State
AVP, and the address within the AVP is a peer that it is able to
exchange DIAMETER messages with, the message MUST be forwarded to the
peer in question. When the Proxy-State AVP's address indicates that
the AVP was locally added, the Proxy-State AVP MUST be removed, and
the original Proxy-State AVP must be restored (if one was present in
the corresponding request). When DIA2 receives the response from DIA3
(in figure 2), it examines the Proxy-State and finds that it was
created by DIA1. Since DIA2 is able to communicate with DIA1, it
forwards the message to DIA1.
The Proxy-State AVP's Address field is 128-bits in length contains
one of the IP addresses of the system that created the AVP, and used
to assist hosts in determining whether a Proxy-State AVP is intended
for the local host. If the host creating the AVP has an IPv4 address,
Calhoun et al. expires January 2001 [Page 28]
INTERNET DRAFT July 2000
and is IPv6 capable, the leading 96 bits MUST be set to zero (0). If
the AVP has an IPv4 address, and the host is not IPv6 capable, the
leading 64 bites MUST be set to zero (0), and the following 32 bits
MUST be set to all ones [16].
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
AVP Header (AVP Code = 33)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 128-bit Address...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-+-+-+-+
6.2.2 Destination-NAI AVP
The Destination-NAI AVP (AVP Code 269) is of type String, MAY be
included in a request, and SHOULD be included in a response message.
The Destination-NAI MUST be in a format consistent with the NAI
specification. When found in a response, the AVP SHOULD contain the
value of the Host-Name AVP that was found in the request.
Since the Destination-NAI AVP allows for a more resilient DIAMETER
network, by allowing a DIAMETER node to send to one of many peers
that can handle a particular realm, implementations SHOULD use it as
opposed to the Proxy-State AVP.
Request messages in transactions that span multiple round trips (e.g.
EAP [7]), the Destination-NAI AVP SHOULD be copied from the previous
response that caused the new request. This will ensure that all
requests forming the transaction will be forwarded to the same target
DIAMETER server.
Calhoun et al. expires January 2001 [Page 29]
INTERNET DRAFT July 2000
(Request) (Request)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
(Host-Name=DIA1@nmo.net) (Host-Name=DIA1@nmo.net)
+------+ +------+ +------+
| | | | | |
| DIA1 +------------------>+ DIA2 +------------------>+ DIA3 |
| | | | | |
+------+ +------+ +------+
^ |
| +------+ |
| | | |
+-----------------------| DIA4 |<----------------------+
| |
+------+
(Response) (Response)
(User-Name=joe@abc.com) (User-Name=joe@abc.com)
(Dest-NAI=DIA1@mno.net) (Dest-NAI=DIA1@mno.net)
mno.net mno.com abc.com
Figure 3: Use of Destination-NAI
When DIA3 (in figure 3) creates the response, it adds the
Destination-NAI AVP with the value that was found in the request's
Host-Name AVP. DIA3 is not able to communicate directly with DIA1,
but it is able to communicate with peers within the mno.com network.
Therefore, it issues the response to any peer in the mno.com network.
When DIA4 receives the response, it examines the Destination-NAI AVP,
and determines that it is able to communicate directly with DIA1, and
forwards the response to it.
6.3 Message Redirection
There are cases where a DIAMETER proxy, known as a broker, may wish
to request that a server contact another directly instead of
forwarding the message (figure 2). This is typically done when the
broker provides simple NAI to Home DIAMETER Server address resolution
services.
In the example provided in figure 4, abc.net's DIAMETER server issues
a request to its broker, which in turn returns a response that
includes the Result-Code AVP set to DIAMETER_REDIRECT_INDICATION (see
section 5.2). When a response is received with the Result-Code set
to this value, the message MUST also include one or more Redirect-
Host AVPs, and optionally the Redirect-Host-Port AVP. The Redirect-
Host AVP contains the IP address to which the request SHOULD be
forwarded to directly. When more than one untagged Redirect-Host-Port
AVPs are found, they contain more than one server that could service
Calhoun et al. expires January 2001 [Page 30]
INTERNET DRAFT July 2000
the request. When more than one tagged Redirect-Host AVP is present
in the message, they contain the various IP addresses of the SAME
host, any of which MAY be used to directly contact the peer.
The above requires that the broker be contacted for all messages in
order to identify the Home DIAMETER server to use for a particular
realm. Since contacting the broker does introduce additional latency,
an implementation MAY cache the information received by the broker,
eliminating the need to contact the broker for multiple messages to
the same realm. The broker MAY include the the Session-Timeout AVP in
the redirect response as a hint to its peer as to how long the cache
entry SHOULD be valid. The peer is not obligated to respect the hint
from the broker.
In the event that the Redirect-Host AVP is tagged, the broker MAY
also add the tag to the Session-Timeout AVP in order to specify the
cache timeout for the particular host.
+------------------+ +---------+
| DIAMETER | | CRL DB/ |
| Broker | | OCSP |
+------------------+ +---------+
^
Request | Response +
| Result Code =
| Redirect
v
+----------+ +----------+
| abc.net | | xyz.net |
| DIAMETER |<------------>| DIAMETER |
| Server | | Server |
+----------+ Direct +----------+
Communication
Figure 4: DIAMETER Broker Returning Redirect Indication
When returning the response with the Result-Code set to
DIAMETER_REDIRECT_INDICATION, the broker MAY also include the
certificates of both the requesting server, and the target server.
These certificates are encapsulated in a CMS-Data AVP [11]. The
requesting server SHOULD forward the certificate that belongs to it
in the subsequent request to the home DIAMETER server.
Figure 5 below provides a more complex network, where the request
must be forwarded to a second broker (Inter-Broker Communication),
and there are a number of proxies between the NAS and the "edge"
DIAMETER Server that communicates with the broker. When Broker A
receives the response that includes the redirect information from
Broker B, it is passed down to abc's DIAMETER server, which in turn
Calhoun et al. expires January 2001 [Page 31]
INTERNET DRAFT July 2000
communicates directly with xyz's server.
+------------+ Request +------------+
| DIAMETER | | DIAMETER |
| Broker A |<--------->| Broker B |
+------------+ Redirect +------------+
^ Response
Request |Redirect
|Response
|
v
+----------+ +----------+
+-----+ +-| abc.net | | xyz.net |
| | +-| | DIAMETER |<------------>| DIAMETER |
| NAS |<->| | | Server(s)| | Server |
| | | | +----------+ Direct +----------+
+-----+ | +----------+ Communication
+----------+
Figure 5: Inter-Broker redirect in a proxied network
6.3.1 Redirect-Host AVP
The Redirect-Host AVP (AVP Code 278) is of type Address and is
returned in a response that has the Result-Code AVP set to
DIAMETER_REDIRECT_REQUEST. This AVP includes the IP address of the
DIAMETER host to which the request MUST be redirected. The presence
of multiple tagged Redirect-Host AVPs with the same tag value,
implies that all of the addresses MAY be used to contact the same
host. When multiple AVPs are found that are un-tagged, or tagged with
different value, they represent separate hosts. Upon receipt of such
a Result-Code, and this AVP, a DIAMETER host SHOULD send the request
directly to one of the hosts.
The broker MAY wish to return the certificate associated with a given
Redirect-Host AVP. This can be returned in a CMS-Data AVP, as defined
in [11].
6.3.2 Redirect-Host-Port AVP
The Redirect-Host-Port AVP (AVP Code 277) is of type Integer32 and
MAY be present when the Redirect-Host AVP is present. The absence of
this AVP implies that the reserved port MUST be used.
7.0 DIAMETER Message Security
Calhoun et al. expires January 2001 [Page 32]
INTERNET DRAFT July 2000
The DIAMETER Base protocol MAY be secured in one of three ways. The
first method does not involve any security mechanisms in the DIAMETER
protocol, but relies on an underlying security mechanism, such as IP
Security. The second method is hop-by-hop security, which SHOULD be
supported by all DIAMETER implementations. The third method is
optional and requires a Public Key Infrastructure [14], and is
documented in [11].
7.1 Hop-by-Hop Security
DIAMETER Hop-by-Hop security provides message integrity and per AVP
encryption, and requires that the communicating entities have a pre-
configured shared secret, similar to the method employed by the
RADIUS protocol. Hop-by-Hop security is very difficult to deploy and
administer in large scale networks and involves symmetric trust,
unlike security based on a public key infrastructure (PKI). PKI is
used for DIAMETER End-to-End security, and is defined in [11]. Hop-
by-Hop security may be desirable in environments where symmetric
cryptography is sufficient or when a PKI is not available.
Figure 6 below provides an example of hop-by-hop security in a proxy
chain. Assuming that the packet was received by DIA2 from DIA1, and
was to be proxied to DIA3, the following steps would be taken:
1. Validating the message's integrity using the shared secret with
DIA1, and removing the authenticated security AVPs.
2. Decrypting any encrypted AVPs using the secret shared with DIA1.
3. Re-encrypting AVPs using the secret shared with DIA3.
4. Computing the message hash using the secret shared with DIA3,
and adding it to the ICV AVP in the DIAMETER message.
(Shared-Secret-1) (Shared-Secret-2)
+------+ -----> +------+ ------> +------+
| | |1 3| | |
| DIA1 +------------------>+ DIA2 +------------------>+ DIA3 |
| | |2 4| | |
+------+ +------+ +------+
Figure 6: Hop-by-Hop Security in Proxy Environments
The above steps that each proxy MUST perform in a proxy chain clearly
describes the security issues associated with hop-by-hop security in
a proxy environment. Since the message integrity is re-computed at
each node in the chain, it is not possible to detect if a proxy
modified information in the message (e.g. session time). Furthermore,
Calhoun et al. expires January 2001 [Page 33]
INTERNET DRAFT July 2000
any sensitive information would be known to all proxies in the chain,
since each node must decrypt AVPs. Therefore, Any AVPs that contain
data that MUST NOT be seen by intermediate DIAMETER nodes MUST be
protected via the mechanism described in the strong security
extension [11].
It is highly recommended that the size of the shared secrets used be
sufficiently long (e.g. 128 bits), and that different shared secrets
be used for both authentication and encryption.
7.1.1 Integrity-Check-Value AVP
The Integrity-Check-Value AVP (AVP Code 259) is of type complex and
is used for hop-by-hop message authentication and integrity.
The DIAMETER header as well as all AVPs (including padding) up to
this AVP is protected by the Integrity-Check-Value. Note that the
Message Length field in the DIAMETER header MUST be set to zero (0)
prior to the ICV calculation. The Timestamp and Nonce AVPs MUST be
present in the message PRIOR to the Integrity-Check-Value AVP. The
Timestamp AVP provides replay protection and the Nonce AVP provides
randomness. Any AVPs in a message that is not succeeded by the
Integrity-Check-Value AVP MUST be ignored.
The following is an example of a message that include hop-by-hop
security:
<DIAMETER Message> ::= <DIAMETER Header, Command-Code = foobar>
<Nonce AVP>
[<Additional AVPs>]
<Timestamp AVP>
<Integrity-Check-Value AVP>
All DIAMETER implementations SHOULD support this AVP.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
AVP Header (AVP Code = 259)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transform ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ...
+-+-+-+-+-+-+-+-+
Calhoun et al. expires January 2001 [Page 34]
INTERNET DRAFT July 2000
AVP Length
The length of this attribute MUST be at least 13.
Transform ID
The Transform ID field contains a value that identifies the
transform that was used to compute the ICV. The following
values are defined in this document:
HMAC-MD5-96[6] 1
The ICV is computed using the HMAC-MD5 algorithm, and the
first 12 bytes of the hash output is included in the data
portion of the ICV AVP. All DIAMETER implementations
supporting this AVP MUST support this transform. Using the
example code provided in [6], the following call would be
used to generate the Integrity-Check-Value:
hmac_md5(DiameterMessage, MessageLength, Secret,
Secretlength, Output)
Key ID
The Key ID field contains a key identifier, which is used to
identify the keying information used to generate the AVP's data
field.
Data
The data field contains the output from the hashing algorithm.
7.1.2 Encrypted-Payload AVP
The Encrypted-Payload AVP (AVP Code 260) is of type complex and is
used to encapsulate encrypted AVPs for privacy during transmission.
Hop-by-Hop confidentiality is achieved by encapsulating all AVPs
which are to be encrypted into an Encrypted-Payload AVP. This
feature SHOULD be supported by DIAMETER implementations.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
AVP Header (AVP Code = 260)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Transform ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Decrypted Data Length | Data ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Calhoun et al. expires January 2001 [Page 35]
INTERNET DRAFT July 2000
AVP Length
The length of this attribute MUST be at least 13.
Transform ID
The Transform ID field contains a value that identifies the
transform that was used to compute the ICV. The following
values are defined in this document:
MD5 1
See section 7.1.2.1 for more information.
Key ID
The Key ID field contains a key identifier, which is used to
identify the keying information used to generate the AVP's data
field.
Decrypted Data Length
The encrypted data length field contains the actual length of
the decrypted data. This field is necessary in order to not
treat the padded data as part of the plaintext.
Data
The data field contains the encrypted payload.
7.1.2.1 MD5 Payload Hiding
MD5 Payload Hiding is supported by DIAMETER for backward
compatibility with existing RADIUS infrastructure.
The plain text (which is a buffer containing one or more AVPs) is
first padded to a sixteen (16) byte boundary with 0 bytes. Since the
encapsulated AVPs have length fields, it is possible to detect their
boundaries, whether or not padding has been done.
One or more Nonce AVPs MUST precede an Encrypted-Payload AVP. An MD5
hash is performed on the:
- last Nonce AVP which precedes the Encrypted-Payload AVP
- the shared authentication secret
This MD5 hash value is then XORed with the first 16 octet segment of
the buffer to encrypt. The resulting 16 octet result is saved as the
first 16 octets of the encrypted buffer. The result is also used to
calculate a new value using MD5:
- the shared authentication secret
- the 16 byte result of the previous XOR
Calhoun et al. expires January 2001 [Page 36]
INTERNET DRAFT July 2000
This value is then XORed with the next 16 bytes. This is done for
each 16 bytes successively in the buffer to encrypt, producing an
equal sized encrypted buffer.
The receiver of a DIAMETER message with an Encrypted-Payload AVP MUST
first check the integrity of the message, either through the ICV, or
the CMS-Data AVP [11] if it protects the Encrypted-Payload AVP. Then
the Encrypted-Payload AVP is decrypted, by reversing the above
procedure, which applied to the buffer will reproduce the plain text
version. The decapsulated AVPs are then used to process the DIAMETER
message in the normal manner.
7.2 Nonce AVP
The Nonce AVP (AVP Code 261) is of type Data and MUST be present
prior to the Integrity-Check-Value AVPs within a message and is used
to ensure randomness within a message. The content of this AVP MUST
be a random value of at least 128 bits. Some crypto algorithms are
known to have weaknesses if a random value is not found early within
the plaintext, therefore it is recommended that the Nonce AVP be
added early in a message if possible.
7.3 Timestamp AVP
The Timestamp AVP (AVP Code 262) is of type Time and is used to add
replay protection to the DIAMETER protocol. This AVP MUST appear
prior to the Integrity-Check-Value AVP or any other message integrity
AVP defined in separate extensions. The value of this AVP is the most
significant four octets returned from an NTP [18] server that
indicates the number of seconds expired since Jan. 1, 1900.
Messages that are older than a configurable maximum age SHOULD be
rejected (see section 10.0) and a response SHOULD be returned with
the Result-Code AVP value set to DIAMETER_TIMEOUT. Note that the
larger the configurable value, the more susceptible one is to a
replay attack. However, one does have to take into account the
possibility for clock drift, and the latency involved in the
transmission of the message over the network. The timestamp AVP
SHOULD be updated prior to retransmission.
A DIAMETER node that receives a message with the Result-Code AVP set
to DIAMETER-TIMEOUT MAY use the time found in the Timestamp AVP
within the reply in order to synchronize its clock with its peer.
When time synchronization is done, the sender MUST NOT change its
local time, but SHOULD adjust the time delta for all outgoing
messages to the peer, and require that its local time be used in
Calhoun et al. expires January 2001 [Page 37]
INTERNET DRAFT July 2000
received messages.
Implementations must be prepared to wrap at the epochal 2038 where
Time values are used, and 0,1,... MUST be considered greater than
2^32-1 at that time.
8.0 IANA Considerations
This document defines a number of assigned numbers to be maintained
by the IANA. This section explains the criteria to be used by the
IANA to assign additional numbers in each of these lists. The
following subsections describe the assignment policy for the
namespaces defined elsewhere in this document.
8.1 AVP Attributes
As defined in section 2.2, AVPs contain vendor ID, attribute and
value fields. For vendor ID value of 0, IANA will maintain a registry
of assigned AVP codes and in some case also values. Attribute 0-254
are assigned from the RADIUS protocol [1], whose attributes are also
maintained through IANA. AVP Codes 256-280 are assigned within this
document. The remaining values are available for assignment through
Designated Expert [12].
8.2 Command Code Values
As defined in section 2.1, the Command Code field has an associated
value maintained by IANA. Values 0-255 are reserved for backward
RADIUS compatibility, and values 256-258 are defined in this
specification. The remaining values are available for assignment via
Designated Expert [12].
8.3 Extension Identifier Values
As defined in section 2.6.5, the Extension Identifier is used to
identify a specific DIAMETER Extension. All values, other than zero
(0) are available for assignment via Standards Action [12].
Note that the DIAMETER protocol is not inteded to be extended for any
purpose. Any extensions added to the protocol MUST ensure that they
fit within the existing framework, and that no changes to the base
protocol are required.
Calhoun et al. expires January 2001 [Page 38]
INTERNET DRAFT July 2000
8.4 Result-Code AVP Values
As defined in Section 5.2, the Result Code AVP (AVP Code 268) defines
the values 0-8. All remaining values are available for assignment via
IETF Consensus [12].
8.5 Integrity-Check-Value AVP Transform Values
Section 7.1.1 defines the Integrity-Check-Value AVP (AVP Code 259)
which contains a field called the Transform. This document reserves
the value 1. All remaining values are available for assignment via
Designated Expert [12].
8.6 AVP Header Bits
There are six remaining reserved bits in the AVP header. Additional
bits should only be assigned via a Standards Action [12].
9.0 Open Issues
The following are the open issues that SHOULD be addressed in future
versions of the DIAMETER protocol:
- AVPs of type 'Time" are 32 bits in size and contain the a
timestamp consistent with NTP [18]. This field is expected to
expire sometime in 2038. Future investigation SHOULD be done to
determine if a 64 bit time format could be used.
- The fact that the Sender's IP Address is used in the
construction of the Session-Id means that the introduction of
Network Address Translation MAY cause two hosts to represent the
same Session Identifier. This area needs to be investigated
further to be able to support DIAMETER hosts on a private
network.
- When additional hashing transforms are supporting by the
DIAMETER base protocol, there SHOULD be a method to negotiate
the transform to be used. This negotiation MUST NOT be prone to
a bidding down attack to the lowest secure transform.
- This specification defines the use of SCTP port 1812. This port
has not been assigned to the DIAMETER protocol, and cannot be
requested until SCTP becomes an RFC.
Calhoun et al. expires January 2001 [Page 39]
INTERNET DRAFT July 2000
10.0 DIAMETER protocol related configurable parameters
This section contains the configurable parameters that are found
throughout this document:
DIAMETER Peer
A DIAMETER entity MAY communicate with peers that are
statically configured. A statically configured DIAMETER peer
would require that either the IP address or the fully qualified
domain name (FQDN) be supplied, which would then be used to
resolve through DNS.
Realm Routing Table
A DIAMETER Proxy server routes messages based on the realm
portion of a Network Access Identifier (NAI). The server MUST
have a table of Realms Names, and the address of the peer to
which the message must be forwarded to. The routing table MAY
also include a "default route", which is typically used for all
messages that cannot be locally processed.
Maximum Age of an outstanding message
Messages older than the maximum age SHOULD be rejected, as
described in section 7.3. The recommended value is 4 seconds.
Shared Secret
The shared secret is a value that is known by two communicating
peers, and is used to generate the Integrity-Check-Value AVP.
There is no default.
11.0 Security Considerations
The DIAMETER base protocol requires that two communicating peers
exchange messages in a secure fashion. This document describes two
security methods that can be used. The first requires no security at
the application layer, but rather relies on an underlying security
mechanism, such as IP Security.
When IP Security is not available, or desirable, the DIAMETER
protocol MAY use hop-by-hop security, which requires communicating
peers to share a long-lived secret. Hop-by-Hop security provides
replay protection by requiring that the communicating peers share a
time source, such as an NTP server. Information of a sensitive
nature, which MUST NOT be seen by any intermediate DIAMETER node MUST
NOT be encrypted using hop-by-hop encryption.
When the DIAMETER protocol is used in an inter-domain network, strong
application level security MAY be required, such as non-repudiation.
Calhoun et al. expires January 2001 [Page 40]
INTERNET DRAFT July 2000
When the communicating peers do require this level of security either
for legal or business purposes, the extension defined in [11] MAY be
used. This security model provides AVP-level authentication, and the
encryption mechanism is designed such that only the target host has
the keying information required to decrypt the information.
12.0 References
[1] Rigney, et alia, "RADIUS", RFC-2138, April 1997
[2] Reynolds, Postel, "Assigned Numbers", RFC 1700, October 1994.
[3] Postel, "User Datagram Protocol", RFC 768, August 1980.
[4] Rivest, "The MD5 Message-Digest Algorithm", RFC 1321, April
1992.
[5] Kaufman, Perlman, Speciner, "Network Security: Private Communi-
cations in a Public World", Prentice Hall, March 1995, ISBN 0-
13-061466-1.
[6] Krawczyk, Bellare, Canetti, "HMAC: Keyed-Hashing for Message
Authentication", RFC 2104, January 1997.
[7] P. Calhoun, W. Bulley, A. Rubens, J. Haag, "DIAMETER NASREQ
Extension", draft-calhoun-diameter-nasreq-04.txt, IETF work in
progress, July 2000.
[8] Aboba, Beadles "The Network Access Identifier." RFC 2486. Janu-
ary 1999.
[9] Calhoun, Zorn, Pan, Akhtar, "DIAMETER Framework", draft-
calhoun-diameter-framework-08.txt, IETF work in progress, June
2000.
[10] P. Calhoun, C. Perkins, "DIAMETER Mobile IP Extensions", draft-
calhoun-diameter-mobileip-09.txt, IETF work in progress, July
2000.
[11] P. Calhoun, W. Bulley, S. Farrell, "DIAMETER Strong Security
Extension", draft-calhoun-diameter-strong-crypto-04.txt (work in
progress), July 2000.
[12] Narten, Alvestrand,"Guidelines for Writing an IANA Considera-
tions Section in RFCs", BCP 26, RFC 2434, October 1998
Calhoun et al. expires January 2001 [Page 41]
INTERNET DRAFT July 2000
[13] S. Bradner, "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[14] Myers, Ankney, Malpani, Galperin, Adams, "X.509 Internet Public
Key Infrastructure Online Certificate Status Protocol (OCSP)",
RFC 2560, June 1999.
[15] Arkko, Calhoun, Patel, Zorn, "DIAMETER Accounting Extension",
draft-calhoun-diameter-accounting-07.txt, IETF work in progress,
July 2000.
[16] Hinden, Deering, "IP Version 6 Addressing Architecture", RFC
2373, July 1998.
[17] ISI, "Internet Protocol", RFC 791, September 1981.
[18] Mills, "Simple Network Time Protocol (SNTP) Version 4 for IPv4,
IPv6 and OSI, RFC 2030, October 1996.
[19] Housley, Ford, Polk, Solo, "Internet X.509 Public Key Infras-
tructure Certificate and CRL Profile", RFC 2459, January 1999.
[20] B. Aboba, G. Zorn, "Criteria for Evaluating Roaming Protocols",
RFC 2477, January 1999.
[21] M. Beadles, D. Mitton, "Criteria for Evaluating Network Access
Server Protocols", draft-ietf-nasreq-criteria-05.txt, IETF work
in progress, June 2000.
[22] T. Hiller and al, "CDMA2000 Wireless Data Requirements for AAA",
draft-hiller-cdma2000-aaa-01.txt, IETF work in progress, June
2000.
[23] S. Glass, S. Jacobs, C. Perkins, "Mobile IP Authentication,
Authorization, and Accounting Requirements", draft-ietf-
mobileip-aaa-reqs-03.txt, IETF work in progress, March 2000.
[24] F. Yergeau, "UTF-8, a transformation format of ISO 10646", RFC
2279, January 1998.
[25] P. Calhoun, A. Rubens, H. Akhtar, E. Guttman, W. Bulley, J.
Haag, "DIAMETER Implementation Guidelines", draft-calhoun-
diameter-impl-guide-03.txt, IETF work in progress, June 2000.
[26] R. Stewart et al., "Simple Control Transmission Protocol",
draft-ietf-sigtran-sctp-10.txt, IETF Work in Progress, June
2000.
Calhoun et al. expires January 2001 [Page 42]
INTERNET DRAFT July 2000
[27] Postel, J. "Transmission Control Protocol", RFC 793, January
1981.
[28] E. Guttman, C. Perkins, J. Veizades, M. Day. "Service Location
Protocol, Version 2", RFC 2165, June 1999.
[29] P. Calhoun, N. Greene, "DIAMETER Resource Management", draft-
calhoun-diameter-res-mgmt-04.txt, IETF Work in Progress, July
2000.
13.0 Acknowledgements
The authors would like to thank Nenad Trifunovic, Tony Johansson and
Pankaj Patel for their participation in the Document Reading Party.
The authors would also like to acknowledge the following people for
their contribution in the development of the DIAMETER protocol:
Bernard Aboba, Jari Arkko, William Bulley, Daniel C. Fox, Lol Grant,
Ignacio Goyret, Nancy Greene, Peter Heitman, Paul Krumviede, Fergal
Ladley, Ryan Moats, Victor Muslin, Kenneth Peirce, Stephen Farrell,
Sumit Vakil, John R. Vollbrecht, Jeff Weisberg, Jon Wood and Glen
Zorn
14.0 Authors' Addresses
Questions about this memo can be directed to:
Pat R. Calhoun
Network and Security Research Center, Sun Laboratories
Sun Microsystems, Inc.
15 Network Circle
Menlo Park, California, 94025
USA
Phone: +1 650-786-7733
Fax: +1 650-786-6445
E-mail: pcalhoun@eng.sun.com
Allan C. Rubens
Tut Systems, Inc.
220 E. Huron, Suite 260
Ann Arbor, MI 48104
USA
Calhoun et al. expires January 2001 [Page 43]
INTERNET DRAFT July 2000
Phone: +1 734-995-1697
E-Mail: arubens@tutsys.com
Haseeb Akhtar
Wireless Technology Labs
Nortel Networks
2221 Lakeside Blvd.
Richardson, TX 75082-4399
USA
Phone: +1 972-684-8850
E-Mail: haseeb@nortelnetworks.com
Erik Guttman
Network and Security Research Center, Sun Laboratories
Sun Microsystems, Inc.
Eichhoelzelstr. 7
74915 Waibstadt
Germany
Phone: +49-7263-911-701
E-mail: erik.guttman@germany.sun.com
15.0 Full Copyright Statement
Copyright (C) The Internet Society (1999). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this docu-
ment itself may not be modified in any way, such as by removing the
copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of develop-
ing Internet standards in which case the procedures for copyrights
defined in the Internet Standards process must be followed, or as
required to translate it into languages other than English. The lim-
ited permissions granted above are perpetual and will not be revoked
by the Internet Society or its successors or assigns. This document
and the information contained herein is provided on an "AS IS" basis
and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DIS-
CLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
Calhoun et al. expires January 2001 [Page 44]
INTERNET DRAFT July 2000
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.
Calhoun et al. expires January 2001 [Page 45]